Rat hole digger



Sept. 19, 1950 R. MITCHELL 2,522, 795 mi nous DIGGER Filed May 14, 1946 2 Sheets-Sheet l BY M Patented Sept. 19, 1950 UNITED STATES PATENT OFFICE.

RAT HOLE. BIGGER Roscoe A. Mitchell, CorpusGhristi, Tex. Application May 14, 1946,. Serial No. 669,624

1 Claim. I 1

My present invention rat hole digger and more particularly to the unitary self-powered type of digger as illustrated and described herein.

The structureof my invention is especially adapted for use in digging the auxiliary or rat holes commonly provided in conjunction with oil well drillings in order that the well equipment may be inserted in the rat hole during installation or while the equipment is undergoing repairs.

The digger of my invention is self-contained and does not require connection with the oil well equipment although it will be understood that the well equipment will be lowered and raised from the rat hole by the conventional well derrick.

In the accompanying drawing I have illustrated one complete example of the physical embodiment of my invention according to the best mode I have thus far devised but it will be understood that various changes and alterations may be made in the exemplified structure within the scope of the appended claim.

In the drawings:

Figure 1 is a top plan view of the rat hole digger of my invention.

Figure 2 is a side elevational view thereof.

Figure 3 is a transverse sectional view at line 3-3 of Figure 2; and

Figure 4 is a sectional view at line 4--4 of Figure 3.

Referring now to the drawings wherein like characters indicate like parts I have illustrated the rat hole digger of my invention comprising the base section 2 and the base section4 secured to the skids B as by bolts 8. The pivotally mounted bails 1 permit the ready placement and removal of the digger by the attachment of a hoisting hook.

A housing II] secured by bolts I l to the base section 2 encloses a prime mover here illustrated as an internal combustion engine l2 having a power shaft l4 and gear l6 thereon. The gear 18 meshes with the gear [6 and. the shaft 20 for the gear I8 is provided with journal supports 22 and 24, and the pinion gear 25.

Upon the base section 4 I have provided the drill rig which consists in the cylinder 26 having its central opening formed with vertical ribs 21 and a peripheral groove 28. A gear ring 29 on the cylinder engages with the pinion 25 to provide rotary movement to the cylinder.

At the lower portion of the cylinder and exterior thereof I have fashioned the shoulder 32 relates to an improved 21' having a diagonal face 34" and a spaced depend-. ing flange 36.

A base ring 38 having one. side thereof di'sposed" angularly to the main portion as at 40 center of the cylinder, andabout this open center I utilize the spaced annular collars 44 and 46,.the outer face of the outer collar 46being tapered as. at 48' and. lying in the same pl'aneas the diagonal face 34 of the cylinder shoulder.

Ball bearings 50 are positioned between the lower edge of the flange 36 and the base ring 38, and these bearings are confined laterally by the spaced collars 44 and 46.

A retaining ring 52 is formed with a lower flange 54 secured by bolts 56 to the base ring 38 and 40 and the upper portion of the retaining ring is formed into a circular rim 58 and a spaced depending flange 60, the rim and the flange forming a ball race for the ball bearings 62.

The outer housing 64 is shown as concave from top to bottom, and the upper inturned flange B6 fits into the groove 30 of the gear ring, while the lower ring 68 is secured to the base ring and the base section through the portion 4|] by means of r The elevated portion of the base ring 318 is secured to the upper nd outer edge of the inclined face as by bolts 18.

In order to support and engage a conventional drill rod such as the Kelly bar, I provide the semi-circular inserts 80 and 82 for the cylinder and formed with vertical grooves 84 for co -action with the ribs 21. When inserted into the cylinder these sections present a rectangular opening as 86 for the Kelly bar, and the sections are prevented from falling through the cylinder by means of the annular shoulder 88 engaging the annular groove 28 of the cylinder. To lugs 90 on the sections 80 and B2 are secured handles 92 to facilitate removal and insertion of the sections.

When during the course of a well drilling operation or when it becomes necessary to repair the well equipment, the rat hole digger of my invention is brought into play and the digger is lifted into position on the derrick floor as described. The drill rod or tube is passed through the cylinder, being hoisted by the conventional derrick, and the sections and 82 are inserted 3 in the cylinder to support and provide power transmission means therefore.

The engine is started and power applied through the gearing whereupon the cylinder is rotated through its ring gear and the rat hole is provided Without disturbing the well digging equipment, building angular braces and supports, or otherwise wasting time and labor.

The self-contained unit of my invention will be ready for instant use whenever desired and will avoid costly delays and be a great saving in the time of operations.

Being unitary in construction, the digger may be hoisted into place and removed therefrom in a minimum of time, and the self-powering construction will avoid the undesirable necessity of disconnecting the well drilling table and the use of additional sprockets and chains or gearing to provide motive power,

Having thus fully described my invention, What I claim as new and desire to secure by Letters Patent is:

A portable rat hole digger, comprising supporting skids, a support mounted on'the skids, the upper surface of the support being inclined, spaced annular collars rising from the upper'surface of the support, an outer housing mounted on the'support and being disposed at an oblique angle with respect to the support, a cylinder mounted on the. support, a dependin flange'on the lower end of the cylinder disposed between the spaced annular collars of the support, said cylinder having an annular shoulder disposed intermediate its ends, a retaining ring secured to the inclined upper surface of the support, ball bearings mounted on the annular shoulder of the cylinder and engageable by said retaining ring, holding the ring in position on the support, a ring gear formed on said cylinder, '2. power shaft and pinion, the pinion engaging the ring gear rotating the cylinder, semi-circular inserts mounted within the cylinder and having an opening in which a Kelly bar is held for rotation, and an inturned flange on the housing fitted in a groove of the cylinder closing the top of the housing.

ROSCOE A. MITCHELL.

REFERENCES CITED lhe following references are of record in the file of this patent:

UNITED STATES PATENTS ,Reed June 8, 1943 

